To enable usb devices :

First you need to modify a configuration file :

use any editor you like (vim,nano, gedit)

I use vim ...

sudo vim (you can use gksudo gedit ...)

Edit (as root) /etc/udev/rules.d/40-permissions.rules

Change this line :

SUBSYSTEM=="usb_device", MODE="0664"
To :

# Edited to enable USB devices with VirtualBox
# Original line commented out
# SUBSYSTEM=="usb_device", MODE="0664"
SUBSYSTEM=="usb_device", MODE="0666"
(the # comments out the first line in case you need to change the file back)

Now in virtual box, select your machine, select usb devices, enable, add usb devices.

Boot your virtual machine. On the bottom of the window is an icon to add usb devices to the virtual machine.

Note: The USB device can be used by either the virtual machine or the host, but not both at the same time. Your usb device will be unmounted when you boot the virtual machine by brute force, be prepared ...